This project provides PDP-11 computer support at various levels for four Becton-Dickinson FACS II and one Coulter MDADS FC/ECS instruments. Data acquisition is via an NIH-designed interface to the computer. Data display and analysis for high sample throughput is the principal system feature. Currently, there are two versions of data acquisition and analysis systems developed and supported by CSL for the Cell Sorter Community at NIH. One version uses a single computer that runs under the RT-11 operating system. Another version, referred to as the RSX system, uses at least two computers. A host computer, a Digital Equipment Corporation (DEC) 11/24 is used to analyze and store data. Satellite computers, one (LSI-11/23) per instrument, are used for data acquisition and are connected to the host through a high-speed direct memory access (DMA) link. The RSX system offers multiuser and multitasking support, improved recordkeeping facilities, and enhancements for data acquisition and data analysis. An RSX system was installed at I, NCI, during the fourth quarter of FY83.